[Charlie]

If you get above 200 or 300 ua on your reading, you should be fine. On tubes that read low, or take a long time for a good reading, crank the heater voltage up to 8 volts for about a half-hour or so. You'll notice a higher reading on your emissions during this time. Later, after the tube has cooled down, turn the tester back on with your heater voltage set back at 6.3 volts. If there's still a good bit of life left in the tube, you should notice a satisfactory reading within 30 to 60 seconds. If it's still slow getting a good reading, your best bet is using a brightener.

Even if you get a lower reading, try running the tube first without a brightener in the set. The picture you get might be just fine. I have some sets that read low, but still produce a nice picture.